| 摘要 |
<p>: By the construction of pipe lines having an outer, sealed mantle tube of plastics and being made of joined, prefabricated pipe elements, particularly heat insulated pipe elements, various types of sealing problems occur in local surface areas of the plastic tubes. According to the invention it is proposed to overcome these problems by drilling out the said local areas into conical holes, which are thereafter closed entirely sealingly by means of complementarily conical stoppers, which are welded into the holes by a welding technique resulting in a surface-to-surface welding between the stoppers and the hole surfaces.</p> |
